The correct breathing is more important than being able to do a "difficult" asana, many neglect the breathing (at least this is my observance).
Inhaling is supposed to be as long as exhaling.
The sound that is created while doing ujjayj breathing allows to check the length of the breathing. Listen to the breath helps to be in the moment.
The asanas are held for 5 breaths, it used to be 8 breaths.
The breathing is supposed to match with the movements.
Correct breathing supports doing the asanas.
When the breath is held, it's a sign that a limit is reached.
Breathing makes the Ashtanga series meditative - the series can be easily performed in an even rhythm.
Inhaling, pause, exhaling, pause, inhaling.
Exhaling while forward bending
Inhaling while lengthening the body and while bending back.
The breath is the secret.